Every now and again there comes along a scientific study that proves beyond reasonable doubt what you instinctively know to be true: wine is good for you, exercise is dangerous, and self-righteous environmentalists are lying, cheating, thieving degenerates.

I’m exaggerating only a little. Do Green Products Make Us Better People?, a paper in the latest edition of the journal Psychological Science, argues that those who wear what the authors call the “halo of green consumerism” are less likely to be kind to others, and more likely to cheat and steal. Faced with various moral choices – whether to stick to the rules in games, for example, or to pay themselves an appropriate wage – the green participants behaved much worse in the experiments than their conventional counterparts. The short answer to the paper’s question, then, is: No. Greens are mean.

The authors, two Canadian psychologists, came up with an intriguing explanation for this. “Virtuous acts,” they write, “can license subsequent asocial and unethical behaviour.” It’s the yin-yang theory of psychology, or “compensatory ethics”, to give it its proper name. Buy an organic potato, then go home and beat your wife with The Guardian. Hop smugly into a green hybrid car, then use it to run over little old ladies doing their shopping.